Upgrading 20.5x8-10 Tires on Pontoon Boat Trailer to Higher Load Capacity Tires


I know this is a recurring topic, but can you provide some advice on replacing/upgrading my pontoon trailer wheels/tires? I have 20.5 8-10 tires on galvanized wheels that are 5 on 5.5. They are load rating F. Boat and trailer weight is under 3,000 lbs and the #84 single axle is 3,500 lb rated. Is there a 13 inch or other size wheel/tire combination that I could upgrade to which would allow a similar load rating with higher speed rating? My assumption is that a 13 inch wheel would “run cooler” on the highway, is this correct? Alternatively, I see that you recommend 205/65-10 tires as a replacement for what I have. Will this tire share the same rim that I currently use? Since 10 inch 5 on 5.5 galvanized wheels are difficult to find, would I consider switching the hubs to 5 on 4.5 or another configuration in order to have more ion in options going forward? If so, are there considerations in hub ion?


Helpful Expert Reply:

The modern equivalent to the 20.5x8.0-10 size tires on your pontoon trailer is the 205/65-10 size, which would fit your existing wheels without issue. The highest rated trailer tire we have available in this size is the Kenda Loadstar K399 Bias # AM1HP56, which features a maximum load of 1,650 pounds at 90 psi. This would give you a combined load of 3,300 for a nice safety margin with your trailer that weighs under 3,000 pounds when loaded. This particular tire does also have an excellent speed rating of 87 mph.

With regards to switching to a larger (and thus higher rated) tire and wheel combo and its effect on temperature, your assumption is correct for a number of reasons. A tire that's larger in diameter would have fewer revolutions on the road and would thus run a bit cooler. Since the larger tire will also have a higher capacity, its sidewalls also wouldn't flex as much which would in turn further prevent the tire from heating up as quickly. The tire itself would also be able to withstand more heat before the potential for failure increases.

As you mentioned in your question, a 5 on 5-1/2 inch bolt pattern isn't too common so if you wanted to upgrade in size to say a 13 inch tire and wheel you would need to also replace the hubs.

A much more common bolt pattern is 5 on 4-1/2 inches like with the etrailer.com # AKHD-545-35-EZ-K for a hub and drum assembly. This will fit the #84 spindles on your trailer. This pattern would give you much greater flexibility in upgrading to a larger tire and wheel if desired.

When upgrading to a larger size tire you just need to make sure you have the available wheel well and trailer frame clearance.

For a 13 inch tire and wheel combo that will work well after switching out your hubs I recommend the Kenda Karrier ST175/80R13 Radial Trailer Tire with 13" Galvanized Wheel # AM31994. This particular tire will have an overall diameter/height of 24 inches (compared to 20.5 inches for what you currently have) and a width of 6.9 inches (which is actually smaller than your current width of 8.1 inches). Since this is a radial ply tire it will also run cooler than your existing bias units because of how the cords are constructed. This tire features a 1,610 pound maximum load at 65 psi and a speed rating of 81 mph.

helpful expert reply by:
Chris R

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